Smog Tied to Higher Risk of Lung Cancer, Heart Failure

WEDNESDAY July 10, 2013 -- There's more evidence that smog boosts a person's risk of both lung cancer and heart failure, with even short exposures to small amounts of pollution harming the body.

A pair of newly published European studies found that regularly breathing in air tainted with even low levels of air pollution raises your long-term risk of lung cancer. That finding came from a review of data from nearly 313,000 people across nine European countries. The study was published online July 10 in The Lancet Oncology.

At the same time, short-term exposure to smog has also been linked to increased risk of hospitalization or death from heart failure, according to a study led by the University of Edinburgh that reviewed data from 12 countries worldwide, published the same day in The Lancet.

The findings of the two studies further corroborate the known health risks of air pollution, said Dr. Albert Rizzo, immediate past chair of the national board of directors of the American Lung Association. He was not involved with the new research.

"On a day-to-day basis, a lot of people who aren't diagnosed with a specific illness may not know the importance of protecting yourself against these pollutants. Insult to your airways on a repeated basis can lead to dire consequences," said Rizzo, section chief of pulmonary/critical care medicine at Christiana Care Health System, in Wilmington, Del.

The lung cancer study assessed the risk of long-term exposure to particulate matter in the air by comparing local air pollution levels to reported cases of cancer, in an effort led by the Danish Cancer Society Research Center.

Researchers found that the risk of lung cancer grew with even tiny increases in the amount of particulate pollution in the air. Particulate pollution is the sort of black sooty smoke produced by diesel trucks and buses and by coal-fired power plants.

For example, consider that a human hair is about 70 micrometers wide. Lung cancer risk rose 18 percent every time the amount of 2.5 micrometer-wide particulates increased by 5 micrograms per cubic meter of air, the study said. Risk rose 22 percent every time the amount of 10 micrometer-wide particulates increased by 10 micrograms per cubic meter of air.

"We found no threshold below which there was no risk; the results showed a picture that 'the more the worse, the less the better," the authors said in a journal news release.

The other study compared air quality conditions in specific areas with reports of heart failure hospitalization or death. Researchers found that smog concentration is closely associated with heart failure hospitalization and death.

More specifically, they calculated that the risk of being hospitalized or dying from heart failure rose by about 3.5 percent with every increase of 1 part per million of carbon monoxide and about 2.4 percent for every increase of 10 parts per billion of sulfur dioxide.

Risk also rose 1.7 percent for every 10 parts per billion increase in levels of nitrogen dioxide, and 2 percent for every increase of 10 micrograms per cubic meter of particulate matter.

The study estimates that a modest reduction in particulate levels in the United States could prevent roughly 8,000 heart failure hospitalizations and save more than $300 million annually.

The researchers speculate that smog causes inflammation of the lungs that spills over and creates stress on the heart.

"Even a healthy young athlete who jogs on a high ozone day is going to feel that exposure," Rizzo said. Less healthy people might end up suffering heart failure from the increased stress.

To protect themselves, people in areas with high levels of air pollution should consider installing HEPA (high-efficiency particulate air) filters in their homes, said Dr. Len Horovitz, a pulmonary specialist at Lenox Hill Hospital, in New York City.

"This is something that people can do in the home or office to filter the air and get some of the particular offenders trapped in filters," Horovitz said. "A toxic substance is going right into the lungs, and I don't think it's a leap of scientific understanding to know it's bad for you when you apply a toxic substance directly to tissue."

People also should avoid going outside during times of heavy concentrations of air pollution, particularly if they are performing strenuous tasks like mowing or exercising, Horovitz said.

For his part, Rizzo said people also should lobby the U.S. Environmental Protection Agency to tighten the nation's clean air regulations.